An undertray trim panel is generally disclosed in DE 10 2012 205 582 A1 which is configured as a diffuser in the rear region of a motor vehicle. Included is a lower flat element formed by way of a trim panel of the rear bumper and not ending freely, but rather curving forward in an arc. In motor vehicles having an internal combustion engine, for example in the front region, components can be situated in the engine compartment in front of, to the side of and, in particular, behind the internal combustion engine, which components are to be flowed around by cool air, in order to be cooled in an optimum manner. The air should be cooler than the air which tends to be warmer and has flowed through the front radiator and the associated fan and then as a general rule flows through the remaining engine compartment. It is possible, however, for the latter air to be cool enough for other components, in particular those which lie closer to the engine. In general, however, the air inlet can also serve for any other type of air supply for units or components, not only for cooling purposes.
In order to cool components behind the internal combustion engine with fresh air which heat up during operation and must not become too hot, what is known as a NACA air inlet can be provided to supply favorable air flow in the undertray trim panel. The air inlet typically extends below the oil sump of the engine and opens into the space which lies behind the engine. A NACA air inlet requires certain minimum dimensions, however, in particular a certain length and height in relation to the vehicle longitudinal direction, in order to operate efficiently, and its lowermost part typically must be at a legally prescribed minimum spacing from the roadway. Therefore, a NACA air inlet typically restricts the packaging space available above it in the engine compartment.
Although the NACA air inlet in the abovementioned document DE 10 2012 205 582 A1 generally has a relatively low overall height, it is sufficient here because only a component which lies directly above it is to be cooled, namely a rear muffler which is additionally arranged in a housing, through which the supplied fresh air flows. In order that flow can also pass satisfactorily onto components which lie further to the top in an engine compartment, the NACA air inlet would also have to reach as far as there, since otherwise a premature split of the cool air flow would take place, in particular as a result of the warmer air which circulates in the engine compartment and has flowed through the front radiator and the associated fan. Owing to its construction, the NACA air inlet commonly has a linearly, obliquely running ramp with a correspondingly relatively large overall height.
It would be desirable to provide a motor vehicle undertray trim panel having an air inlet in such a way that it both takes up relatively little space in the engine compartment, in particular in the vertical direction, but also supplies components which lie in front of, to the side of or behind the internal combustion engine with cooling fresh air in an optimum manner. It would be desirable that this function be ensured in a manner which is as neutral as possible with regard to harmful resistances, such as vehicle air resistance.